This invention relates to pyridinium derivatives which are useful as drugs. In more detail, this invention relates to the compound (3-bromo-5-[N-phenyl-N-[2-[[2-(1,2,3,4-tetrahydro-2-isoquinolylcarbonyloxy )ethyl]carbamoyl]ethyl]carbamoyl]-1-propylpyridinium nitrate) of the formula: ##STR2## which is useful as a platelet activating factor (PAF) antagonist.
PAF is a phospholipid which is a chemical mediator present in the body. It has been clarified that PAF plays an important role in allergy, anaphylaxis, and inflammation in vivo, having powerful hypotensive action and platelet agglutinating activity. PAF, when given to an animal, can cause shock resulting in death. Shock symptoms caused by PAF are very similar to those caused by endotoxin, and PAF is known to take part in endotoxin-shock.
Although various compounds have been shown to be PAF-antagonistic, only a few of them are useful PAF antagonists in vivo. Moreover most of the useful PAF antagonists in vivo are restricted in their dosing or have problems in their stability as drugs.